Investigator William Wisting makes a frightening discovery: A corpse has been found among the spruce trees in a Norwegian Christmas tree field, and turns out to have links to a sought after American serial killer.

With the help of FBI agents Maggie and John, Wisting tracks serial killer Robert Godwin to a remote farm, but do they keep the mission secret from the press before Godwin runs?

Wisting and the FBI suspect that Godwin may be behind twelve cases of missing persons in Norway. Vidar Haglund is released from prison, and Line questions the circumstances surrounding Viggo's death.

Line's obsession with Viggo's death leads to a quarrel with her father. Wisting and the FBI find more of Godwin's victims, and the FBI agent John makes a mistake that has serious consequences.

Lines and Wistings investigations are linked, and the search for the serial killer becomes increasingly intense. At the same time, Wisting's worst nightmare becomes reality.

Just as Wisting is hailed as a hero, he faces accusations of evidence tampering in a previous murder case, leading to Vidar Haglund's potentially wrongful conviction. Line tries to keep her father out of the headlines, by chasing a news story on a recent murder.

An internal investigation of Wisting begins after his suspension. Torunn leads the investigation about a missing woman. Line runs into an ex when she works on her Ravneberg article.

Wisting tries to save his reputation by conducting his own secret investigation into the Cecilia case. Torunn believes that Linnea is behind her own disappearance, but her parents are convinced that she is in danger.

Wisting takes desperate methods to show his innocence, while the internal investigation looks more closely at his entire department. Benjamin examines who can lie behind Linnea's disappearance.

Wisting takes the help of a former colleague to solve Cecilia's murder, and to figure out who fiddled with the evidence. Line finds a video that links the charges against Wisting to Linnea's kidnapping.

Wisting and his team are warned about a cruel crime scene in Larvik. The severed head of a young asylum seeker is found on a stake in the middle of the square. FBI agent Maggie Griffin returns to assist in the case.

When a corpse appears in the net of a local poacher, the two killings are linked. Line suspects that Wisting has had a relationship with the manager at the care center.

Maggie is forced to share information, which she has previously kept secret from Wisting. The investigation takes a whole new turn, and leads Wisting and Maggie on a new hunt across the border into Sweden.

In Sweden, Wisting and Maggie find a former victim. Together with the Swedish police, they are drawn into a fierce police action, and the final settlement is both intense and surprising.